In designing of a mobile telephone network, the placement and performance of radio base stations must be designed so as not to create any radio wave dead zone with a minimum required number of radio base stations, and in order to achieve this, radio wave propagation analysis is performed.
There are two types of known techniques for deriving the electric field intensity distribution of a radio wave emitted from the antenna of a radio base station by radio wave propagation analysis: statistical methods and geometric optics methods. In a statistical method, trends of radio wave propagation characteristics are derived by actually measuring the electric field intensity in various conditions, and the electric field intensity distribution is estimated from the results. Meanwhile, in a geometric optics method, also known as the ray-trace method, a radio wave emitted from the antenna is likened to and is expressed as a set of rays, and the electric field intensity distribution is estimated by deriving all the losses including the propagation distance loss between the transmission point and the reception point, and the reflection loss and transmission loss caused by obstacles in the middle. Further, the geometric optics methods are roughly divided into imaging methods and their improved versions, ray launching methods.
For instance, Patent Document 1 describes a radio propagation simulator in which reception points are disposed on the wall on each floor of a building, the reception level of each reception point is calculated using the ray-trace method, and a two-dimensional map and three-dimensional map are color-coded and displayed according to the reception level.    [Patent Document 1] Japanese Patent Kokai Publication No. JP-P2002-44034A